Recent Advances on the Pragmatic Roles of Phytomelatonin and Its Exogenous Application for Abiotic Stress Management in Plants

Melatonin (N-acetyl-5-methoxy-tryptamine), derivative of tryptophan, manifested as a conserved domain, which is ubiquitously apportioned from bacteria to higher organisms extending to fungi and algae as well. Melatonin is entailed in umpteen developmental processes of plants, including stress responses. The pleiotropic impact of melatonin in regulating transcripts of manifold genes validate its imperative contribution as multi-regulatory substance. Albeit, the progressive research regarding plants is yet prelusive in contrast to orthodox melatonin physiology in animals. This reinforces the exigency for comprehensive reassessment pertaining to its potential in biochemical and physiological processes, anti-stress response against abiotic stimulators (temperatures, salinity, drought, toxins, etc.), detoxification mechanism, and its other salubrious effect. Stressors are known to create RNS and ROS, which induces oxidative damage in plants. Cellular deterioration and mortality are a result of negligence toward oxidative damage. Tremendous quantum leap has been made in comprehending, how melatonin safeguards plants against abiotic stress. Here, focus will be on mechanistic basis of melatonin-mediated protection to abate abiotic stress. Abiotic stress induces melatonin synthesis and this redeeming upsurge in melatonin succors plant to thrive under stress conditions. Melatonin is considered an excellent antioxidant because it effectively scavenges a wide range of RNS and ROS. Melatonin maintains ROS levels in peculiar ways: (a) chemical interaction between melatonin and ROS, causing their inactivation and (b) melatonin-induced activation of SOD, POD, APX, CAT, and GPX leads to ROS detoxification. The contemporary study gives a comprehensive review on abiotic stress response of melatonin, particularly, its mitigating impact when applied exogenously in plants under environmental stress conditions. The commentary will allow the researchers to comprehend the prevailing plant stress conditions and further contemplate the tendency of phytomelatonin in crop research.